RESUMEN
Excess triglycerides from the diet are stored in structures called lipid droplets in adipose tissue. Genome-wide RNAi screens have identified mRNA splicing factors as important for lipid droplet formation; however, the full complement of splicing factors that regulate lipid storage is not known. Here, we characterize the role of snRNP-U1-70K , the gene encoding for a splicing protein involved in recognizing the 5' splice site in introns, in regulating lipid and carbohydrate storage in the Drosophila fat body. Decreasing snRNP-U1-70K specifically in the fly fat body resulted in less triglyceride, glycogen, and glucose in each fat body cell. Consistent with these decreased nutrient storage phenotypes, snRNP-U1-70K-RNAi flies ate less, providing a potential cause for less lipid and carbohydrate storage in these flies. These data further support the role of mRNA processing in regulating metabolic homeostasis in Drosophila .
RESUMEN
Polyamines are small organic cations that are important for several biological processes such as cell proliferation, cell cycle progression, and apoptosis. The dysregulation of intracellular polyamines is often associated with diseases such as cancer, diabetes, and developmental disorders. Although polyamine metabolism has been well studied, the effects of key enzymes in the polyamine pathway on lipid metabolism are not well understood. Here, we determined metabolic effects resulting from the absence of spermidine synthase (SpdS) and spermine synthase (Sms) in Drosophila. While SpdS mutants developed normally and accumulated triglycerides, Sms mutants had reduced viability and stored less triglyceride than the controls. Interestingly, when decreasing SpdS and Sms, specifically in the fat body, triglyceride storage increased. While there was no difference in triglycerides stored in heads, thoraxes and abdomen fat bodies, abdomen fat body DNA content increased, and protein/DNA decreased in both SpdS- and Sms-RNAi flies, suggesting that fat body-specific knockdown of SpdS and Sms causes the production of smaller fat body cells and triglycerides to accumulate in non-fat body tissues of the abdomen. Together, these data provide support for the role that polyamines play in the regulation of metabolism and can help enhance our understanding of polyamine function in metabolic diseases.